"I am moved, enormously moved but I am happy... it's the start of a great adventure," Platini said.
"I want to thank everyone who have stayed loyal to me. I'm delighted to be able to represent European football."
The Frenchman, who plans to reduce the number of Champions League places open to the big national leagues, used his final speech before the vote to emphasise the importance of football as a sport rather than a business.
"Football is a game before it is a product, a sport before it is a market and a show before it is a business," said Platini on Friday.
"Italy, England, Germany and Spain should have three clubs each in the Champions League so that teams from other leagues that are not in the same financial bracket can compete with them on the pitch," he said in his manifesto before the election.
After leading France to victory in the European Championship in 1984, Platini, who scored nine goals in five games at the tournament, retired in 1987 and began working with Uefa as a member of the technical development committee the following year.
|Golden handshake: Platini, left, is congratulated|
by Fifa President Sepp Blatter [AFP]
He was then a co-organiser of the successful France '98 World Cup, and in the same year became a personal adviser to Fifa president Sepp Blatter, who in turn endorsed him in the Uefa presidential election.
Other than Platini wanting to limit the number of places in the Champions League to a maximum of three, there was little difference between the two campaigns, with both candidates highlighting the need to further the fight against racism, and tackle the issues of doping, match-fixing and illegal betting.
The lack of major disagreement between the candidates meant the election was largely a friendly one, at least until the intervention of Blatter, who gave his public support to his friend Platini on the eve of the election in a move that infuriated Johansson.
"I thank Joseph Blatter for praising our work, but I can't appreciate the way the Fifa president interfered in the Uefa election," Johansson said before the election.
"It is not up to the president of Fifa to decide, it is up to the Uefa congress."
Johansson, who was given a standing ovation by Uefa members and named as an honorary president of the organization, oversaw huge developments in European football during his 16 years as President, but was criticised for losing touch with the grass roots of the sport.
Platini became the sixth president of the Geneva-based Uefa which was established in 1954, and the second Frenchman after Jacques Georges (1984-1990) to occupy the post.